Electrical treatment of water for the purpose of reducing hardness



June 13, 1939. A. J. PIERPOINT ET AL 2,161,933

ELECTRICAL TREATMENT OF WATER FOR THE PURPOSE OF REDUCING HARDNESS Filed Oct. 14, 1955 W4 7'70/Q/VE y Patented June 13, 1939 I Q I ELECTRICAL TREATMENT OF WATER FOR THE PURPOSE OF REDUCING HARDNESS -Albert John Pierpoint and Reginald Henry Crouch, London, England Application October 14, 1935, Serial No. 44,989 In Great Britain October 15, 1934 6 Claims. (Cl. 204-25) Applications have been filed for patent in mg a simple arrangementof a plurality of elec- Great Britain, No. 29,508 filed October 15, 1934, trode elements more particularly for thetreatand No. 35,266 filed December 7, 1934. ment of water; and I This invention relates to apparatus for the Fig. 4 s a Similar V ew o 3 t S ows a 5 treatment of liquids by passing an electric cur-' modified form of apparatus. 6 rent therethrough and particularly for the treat- As already me the p s of treating ment of water in order to reduce the hardness Water co s s s in discharging an e ectr c alteror the efiects thereof.. hating current of a selected value through the The hardness in water is commonly removed mass of water to be treated and the alrange- In by a chemical process which serves to withdraw ment adopted for e p p e is a am 10 the particular impurities to which the hardness cally illustrated in Fig. in which i is a metal is due, the water resulting from such treatment tank containing the water to be treated, and 2 being generally described as tasting flat. We are electrode elements of the form more fully have found, however, that by discharging elecdescribed below. .In order to obtain the required is trio alternating current of a particular value ha get e t I is Connected to one side through the water to be treated, it is possible of a source of alternating current and the electo improve its qualities, not by the removal of trodes are connected to the other side as shown those impurities causing hardness, but by the through the circuit breakers 3 and fuses 4. Furmodiflcation of the physical properties in such ther, as it is also necessary to be able to adjust a way that the well known results of hardness the value of the discharge to suit the particular 20 in water no longer have a deleteriou effect. conditions, variable condenser units 5 are incor- Thus, water which has been treated in this way porated in the circuit. .The return half of the may be evaporated, the residues being inthe circuit as shown is not essential to the operation form then of a mud instead of a hard scale as of the apparatus, since an earth return would would normally be the case. serve the same purpose, but a direct return is 25 In short, the constituents causing hardness em e required y the Public authority are not removed, but merely a change in physlcerned. It will be understood that the tank I ca] properties i brought. ab ut merely serves as an electrode and can take any We have further found that in order for the other Suitable form, e- 'r it y be afforded y treatment to be consistently successful, it is P O a P p line. 0 by a element serving 30 necessary to ensure that all the water to be merely as an de. treated hall pass i close r i t t t elec- In order to ensure most-efficient treatment it trode or electr de from which t current 1 is necessary to bring the water being treated into di h and one obje t of the invention is as intimate a contact as possible with the electo provide a apparatus which will engine t trode and for this purpose an electrode element 35.

t b d e such as that illustrated in Fig. 2 may be cm- A further object is to provide an electrode ele- Ployed, comprising a cylindrical y 6 aving ment for such an apparatus which will enable a Perforated pp closure cap 1 and a closed th water t b passed in 01056 proximity t the lower end. The walls of the element are pierced o electrode for treatm t, at their lower ends by a number of holes at 8 40 Suitable current values for the treatment of s that wat r e r n y th n y w ut Water range between 0.01 and 0.49 milliampere, again. In the bottom of the hollow element 6 with the electrical pressure between the two .an insulating support 9 is fitted which serves to electrodes ranging between 0.1 and 0.7 volt, receive one' end of a carbon or metal electrode For the better understanding of the invention, 2 and maintain the latter in an upright position 45 'referencewill now be made to the accompanycoaxial with the element body 6. The electrode ing drawing illustrating various examples of con-. 2 extends almost to the top of its containing struction in which: element and is at its upper end provided with Fig. 1 is a diagrammatic view illustrating a a lead ill by which it can be connected to the typical circuit arrangement embodying features source of current. This form of electrode ele- 50 of the invention. ment is especially suitable where the water is Fig; 2 is a sectional elevation showing the pretreated as it is supplied to a cistern as in a doferred construction of electrode element designed mestic general Wa upp y System In this more particularly for use with water;. case the required number of electrode elements Fig. 315 a semi-diagrammatic elevation showis preferably arranged to constitute an outlet 56 from a small container into which the water to be treated is supplied from the mains, the electrode elements themselves discharging into the cistern. Thus. in the example shown in Fig. 3 a rectangular receptacle II constituting such small container is suspended in the usual cistern I under the water inlet with its base Just below the normal water level of the cistern I as shown. The top of the receptacle II is left open and the water which would normally enter the cistern I is thus fed into the receptacle II. The bottom of the latter is provided with a number of apertures, each aperture having secured in it one of the electrode elements illustrated in Fig. 2 the leads I0 from which are connected to a common lead I02: and then througha circuit such as is illustrated in Fig. l to the source of current.

The number of elements 6 arranged in the lower side of a receptacle II will depend entirely upon the volume of water flowing therethrough. A four-electrode unit having an effective electrode surface area of about 48 square inches or 12 square inches per'electrode is adequate for the treatment of -20 gallons of water per hour passing through the receptacle for domestic uses, or 70 gallons per hour for de-scaling only.

Generally speaking, in order to determine the requisite number of electrode elements when treating water, it may be assumed that the rate of flow should not exceed 0.13 gallon per electrode per minute for scale prevention for 'an electrode having a total surface area of 12 square inches, or 0.1 gallon per electrode per minute for domestic purposes. Slower rates than these may, of course, be used with advantage.

Where greater efliciency is required the flow of water may be caused to take place through two electrode stages as illustrated in Fig. 4, in which the receptacle II is enlarged and a receptacle' Ila: is arranged within it at one end. A set of electrode elements 6 is arranged to pro- .Iect horizontally from the wall of the receptacle Ila: and these elements are supported at their other ends in the wall of the receptacle I I. The water to be treated is supplied to the receptacle Ila: and thus has to pass the two sets of electrodes 6 before reaching the main tank I.

The location of the receptacle I I is, as referred to above, such that the bottom is below the normal water level in the cistern I and thus all the elements 6 are immersed in the water contained in the cistern. It should be understood that the total immersion of the elements 6 is not essential but it has been found that the best results have been obtained in this way. Further, it is not essential for the elements 6 to'project downwardly, even where only one set is employed; the horizontal arrangement of Fig. 4-could be used alone. v

The electrode element illustrated in Fig. 2 could even be incorporated in a pipe line if required.

The common wire Ila: is connected to the source of current through a fuse 4 rated at milliamperes, and through a variable condenser unit 5 and also through a circuit breaker I to one side of the mains, as shown in Fig. 1. The

other side' of the mains is connected to the cistern I in which the treated water is contained. It is not important whether the mains afford a supply of direct current or alternating current, since by adjusting the value of the variable condenser unit 6 an alternating current of very small proportions, for instance, between 0.01 and 0.49 milliampere' can be obtained. It is possible to obtain this small alternating current from direct current sources, since it has been found that commercial direct current has a sufficient component of alternating current to suffice for the treatment. As the condenser unit 5 is arranged in series with the electrodes 2, the passage of direct currents is effectively prevented.

Preferably, the condenser unit variation is obtained by the use of individual strip condensers of small value. With the aid of an arrangement of two short-bus bars the value of the condenser unit formed by connection of the strip condenser elements across the bus-bars may be changed at will, either by adding a further strip condenser or removing one. In this way, when the desired capacity has been reached there is no fear of the capacity being accidentally changed.

The value of the current required is found to 'vary in every installation within the limits referred to and in view of the delicacy of adjustment required it is preferable, where a large number of elements 6 are employed, to group them under the control of individual circuits.

In operation, the circuit breaker 3' on thecontrol panel is closed and an alternating current within the range already referred to is allowed to discharge from the electrodes 2 to the cistern I (Figs. 3 and 4). By adjusting the capacity of the series condenser 5 the total current flowing through the body of water may be adjusted to a particular value. It is this total current which must-be carefully kept within the limits specified.

The receptacles II, IIa: are preferably constructed of teak, glass or the material known under the registered trade-mark Bakelite". The part 6 of the element shown in Fig. 2 is preferably made in Bakelite in order that any corrosion likely to take place is reduced to a minimum.

It is clear that where a large quantity of water is to flow through a receptacle the stream might be too great to be properly dealt with by a single one. In this case the invention contemplates the provision of a header adapted to break the stream into a number of separate and independent streams, each of which could be arranged to discharge into a separate receptacle with the requisite number of electrode elements mounted therein.

It will be apparent that the invention has particular value from its commerciaLaspect since when boiler feed water is treated the normal hard scale forming upon the boiler tubes and the internal working parts of the boiler would be eliminated. Instead of this hard scale a readily-removable soft mud would be the only result.

We claim:

1. In apparatus for. the electrical treatment of water, an electrode element comprising 9. cylindrical body havingperforations for the outlet of water, a closing upper cap therefor having perforations-for the inlet of water, an electrode in the cylindrical body, means in the cylindrical body for supporting the electrode to prevent displacement thereof, a conductor projecting through said cap for connecting the electrode to a current supply, means for supplying water through the perforations in said closing cap, a second electrode'separate from said electrode element with which the water is in contact, and a conductor connecting said second electrode, to a current supply.

2. In apparatus for the electrical treatment of water, an electrode element comprising a cylindrical body having perforations for the outlet of water to be treated, a closing upper cap therefor having perforations for the inlet of water, an electrode in the cylindrical body, means in the cylindrical body for supporting the electrode to prevent displacement thereof, a conductor projecting through said cap for connecting the electrode to a current supply, means for supplying water through the perforations in said closing upper cap, a conductive container for the water, electrically separate from said electrode element, in which said element is arranged, and a conductor connecting said container to a current supply.

3. In apparatus for the electrical treatment of water, an electrode element in the water comprising a hollow casing of insulating material having inlet and outlet apertures, an electrode enclosed in said casing, means in the casing for supporting the electrode to prevent displacement thereof, a conductor projecting through said casing connecting the electrode to a current supply, means for supplying water to the inlet to said casing, a second electrode separate from said electrode element with which the water is in contact, and a conductor connecting said second electrode to a current supply.

4. In apparatus for the electrical treatment of water, an electrode element comprising a hollow casing oi insulating material having inlet and outlet apertures for the water to be treated, an.

electrode enclosed in said casing, means in the casing for supporting the electrode to prevent displacement thereof, a conductor projecting through said casing connecting the electrode to a current supply, means for supply! water to the inlet to said casing, a conductive container with which the water is in contact, electrically separate from said electrode element, in which said element isarranged, and a conductor connecting said container to a current supply.

. 5. Apparatus for the electrical treatment of water, comprising a metal container for water,

at least one electrode element arranged therein to be immersed in the water, said element comprising an electrode, a hollow casing of insulating material enclosing said electrode, means in the casing for supporting the electrode against displacement, said casing having an inlet at one end connected to a supply of water and an outlet for the discharge'of water'to the container, and conductors connecting the electrode and container respectively to a current supply.

6. Apparatus for the electrical treatment of water, comprising a metal container for water, a receptacle in the container partially submerged therein, a supplemental receptacle within the first mentioned receptacle, an electrode element having one end anchored in the wall of the supplemental receptacle and extending into said receptacle and another electrode element anchored in the wall of said receptacle and extending into the container, each of said electrode elements comprising an electrode, a hollow casing of insulating material having an inlet and outlet and enclosing said electrode, meansin the casing for supporting the electrode against displacement and being anchored to thelr'respective'receptacles with their inlets in communicationv with the interiors thereof, and conductors connecting the electrodes and container respectively to a current supply.

ALBERT JOHN PIERPOIN'I'. REGINALD HENRY CRQUCH. 

